Self-powered electronic door or passage locks have been known for some time. U.S. Pat. No. 3,733,861 to Robert W. Lester discloses a self-powered door lock having a handle operated generator for providing said power. Most electronic door locks utilize a battery or hard wiring directly or indirectly attached to a utility power source to provide either 110 or 220 volt power or some other desired voltage to the lock. For battery or hard wired house power installations, adequacy of electrical power is not a major concern due to the very large energy source available to power the lock controls.
However, in contrast, the capability of storing significant electrical energy is very limited in a self-powered lock due to the lack of a continuous source of power to operate the lock and the relatively small amount of electrical energy that may be stored within a power storage capacitor within the lock. Voltage levels on capacitors deteriorate with the use of the stored electrical energy to power and operate electronic lock controls. When the stored electrical charge deteriorates below a predetermined level, the remaining energy stored in the capacitors results in voltage levels ineffective to power the lock controls reliably. If uncontrolled, the energy stored in the capacitor dissipates and/or decays until a voltage detector detects the capacitor voltage level falling below the threshold required for reliable electronic control operation of prior locks.
Upon detection of the voltage dissipating and falling through the minimum operating voltage threshold, the detector ceases to provide an output, terminating enablement of the electronic controls. Thus, considerable power is wasted after the lock operations are complete and prior to termination of enablement of the electronic controls, which could otherwise be conserved because the minimum operating voltage threshold must be set well below the level at which the power to the electronic controls, particularly the microprocessor 20, could otherwise be terminated, in order to prevent premature cutoff of lock operations and, particularly, operations of the microprocessor which typically provides the control for the lock.
A self-powered lock must rely on operation of an input (manual input) to the generator to power the lock before each usage. It is desirable to use conserved electrical energy in the capacitor to act as a capacitor pre-charge. The capacitor pre-charge reduces the amount of manual, mechanical input required by the lock to bring the charge level of the power supply capacitor to a full initial operating charge level.
The need for multiple handle or handle lever pumps to power a lock is undesirable if it is required on every use of the lock. If the lock only requires a single handle-lever pump on most of the lock operations, a few operations requiring either two or more pumps may be tolerated by the operator without the operator having a sense or feeling of lack of proper operability.
Where excessive mechanical input is required to power the lock system, as perceived by the operator, the human factors considerations may become paramount in the selection and installation of such self-powered locks. Self-powered locks present many advantages not provided by battery powered or utility powered locks, but those advantages are overcome when the operator perceives the lock as requiring too much operational movement in order to cause the capacitor to be charged and the lock operated reliably. The perception of reliable operation is then lost to the point where a self-powered electronic lock may not be considered for a particular use or location.